Fix start date of copyright notice to match other files in repo

src/autogen.sh

 #!/bin/bash
 
-# Copyright [2020-2021] EMBL-European Bioinformatics Institute
+# Copyright [2018-2021] EMBL-European Bioinformatics Institute
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.